1. Field of the Invention
The present invention relates generally to tube and shell type catalytic reactors having a large number of catalyst containing tubes which are supported in a reactor chamber by upper and lower tube support sheets and which contain catalyst pellets for accomplishing a catalytic reaction with a fluid flowing through the catalyst containing tubes. More particularly, the present invention concerns a testing system for measuring differential pressure of the catalyst containing reaction tubes by introducing pressure at a predetermined flow rate into selected tubes and by reading the back-pressure of the tubes through a transmitter.
2. Description of the Prior Art
Tube and shell type catalytic reactors are typically of cylindrical configuration, having a cylindrical outer pressure containing wall for containing reaction fluids. Upper and lower tube sheets are typically welded to the upper and lower ends of the outer cylindrical wall or shell, so as to be oriented in parallel relation with one another. Intermediate tube sheets, between the upper and lower tube sheets, may also be mounted to the outer shell in the same manner. The reactor tubes are typically welded to the upper and lower tube sheets at a multiplicity of holes in the tube sheets, so that process fluids may flow from above or below the tube sheets through the passages of the reactor tubes and thus through the catalyst pellets that fill or partially fill the reactor tubes, thus causing the catalyst to react with the process fluid to provide the desired reaction and yield a desired fluid product. Tube and shell type catalytic reactors also have upper and lower domed closures that are typically removably secured to the cylindrical outer shell by means of a multiplicity of bolts or threaded studs. The upper and lower domed closures are removable to permit the reactor to be serviced, repaired or overhauled.
From time to time the catalyst pellets within the reactor tubes will become substantially spent and the quality of the reaction thereof with the process fluid will become degraded. By conducting periodic tests of the reacted product being yielded by reaction with the catalyst of the reactor tubes, a determination can be made to shut down the reactor and overhaul the reactor by removing the spent catalyst from the reactor tubes and replacing the spent catalyst with new catalyst material. The condition of the catalyst within the reactor tubes can sometimes be detected by measurement of the back pressure of gas, typically air, being forced through the reactor tubes at a predetermined pressure and rate of flow. This test will also permit any leaking reactor tubes to be detected, so that they can be taken out of service by welding plugs into the upper and lower tube openings. Obviously, to permit differential pressure testing to be accomplished the reactor must be taken out of service and at least one of the upper and lower domed closures must be removed to permit access to the ends of the reactor tubes.
Differential pressure testing of reactor tubes is considered necessary after spent catalyst has been replaced with new catalyst material. If the tubes have been properly filled with catalyst material, each of the multiplicity of reactor tubes will have substantially the same back pressure when differential pressure testing is accomplished. If any of the reactor tubes are improperly filled, the catalyst material thereof can be removed and the tube can be refilled. If not properly filled, certain catalyst tubes of the reactor can develop hot spots within the reactor which may cause the reactor to degrade earlier than expected or it can cause improper reaction to occur, so that the quality of the resulting product can be less than optimum.
An apparatus for differential pressure testing of the filled reactor tubes of tube and shell type catalytic reactors has been developed and utilized. This apparatus permits manual selection and differential pressure testing to be accomplished, one tube at a time. Thus, with many tube and shell type catalytic reactors having as many as 20,000 reactor tubes and some reactors having from 40,000 to 80,000 reactor tubes, this manual testing apparatus is typically utilized by randomly testing selected reactor tubes after the tubes have been filled with catalyst material. This single tube testing apparatus presents some test data in the form of a visual back pressure indication, but does not provide any sort of read-out that can be inspected and maintained as a record. This apparatus is composed of interconnected pipe sections having a tube engaging lower resilient element through which air is permitted to flow into the selected tube. A pressure regulator is mounted to the piping to regulate air pressure being delivered to the unit via a supply hose that is connected to the piping by a quick-disconnect fitting, with the air supply being controlled by a simple lever operated on-off or open-close valve. A pressure gauge is provided in the piping to visually indicate the air pressure being supplied and a differential pressure monitor is also mounted to the unit for visual inspection by the person using the apparatus and being coupled by a tube to the piping at a point below an orifice element. To enable the tapered lower resilient element of the unit to establish sealing engagement with a selected reactor tube, a lateral pipe section is provided which is engaged by the foot of the user to permit sufficient downward force to be applied to deform the tapered lower resilient element against the reactor tube.
It is desirable to provide a mechanism for simultaneously conducting differential pressure testing of a plurality of reactor tubes, for example 8 or 10 tubes to facilitate rapid and simplified reactor tube testing so that all of the reactor tubes of a tube and shell type catalytic reactor can be tested. It is also desirable to provide the test results of differential pressure reactor tube testing in the form of an electronically documented read-out that can be presented in the form of a paper or hard copy, permitting the state of all of the reactor tubes to be indicated and a permanent record to be established. Further, it is desirable to provide a rather complex reactor tube differential pressure testing system that is simple and efficient for rapid use by unskilled workers and which yields quality test results.
The differential pressure testing system of the present invention accomplishes testing of each of the multiplicity of catalyst containing reactor tubes of a tube and shell type catalytic reactor and provides a permanent electronic and or hard copy record of the test of each of the reactor tubes, thereby enabling the owner or operator of the reactor to determine at any given point in time if the reactor is performing properly or if it is in need of cleaning and catalyst changing in order to meet desired performance standards.
Though not limiting, the invention may be practiced by locating on the upper tube sheet of the reactor at least one and preferably a plurality of test carts, with each of the test carts connected by electrical and pneumatic umbilical with a control cart which is preferably located off to the side of the upper tube sheet or plate of the reactor. Four test carts are shown in the drawings but more or less may be used if desired. Though one control cart is shown, more than one may be utilized, each having umbilical connection with one or more test carts.
The control cart contains a computer having a memory system and may also include a computer driven printer which produces a hard (paper) copy of test data for each of the tubes that is tested. The computer memory may be downloaded to a larger, permanent memory system if desired so that the test data may be available for comparative use with subsequently acquired test data if desired or used in any manner that benefits the reactor owner or reactor service contractor. The control cart has connections for compressed air or other test gas under pressure and for electrical power, typically 120 v A/C. Electrical, ethernet computer conductors and pneumatic conductors are provided in an umbilical cable for each of the test carts and are received by umbilical connections of the control cart.